Process for the manufacture of 4-vinylcyclohexene



United States Patent O1 fice 3,526,672 PROCESS FOR THE MANUFACTURE OF4-VINYLCYCLOHEXENE Nicodemus E. Boyer, Parkersburg, W. Va., and MarvinP. Weaver, Belpre, Ohio, assignors to Borg-Warner Corporation, Chicago,[1]., a corporation of Delaware No Drawing. Filed Jan. 14, 1969, Ser.No. 791,182

Int. Cl. C07c 3/10 U.S. Cl. 260-666 11 Claims ABSTRACT OF THE DISCLOSUREA process for the dimerization of 1,3-butadiene to 4- vinylcyclohexenemay be practiced to produce high yields by the use of certain catalystsystems which include (1) secondary aromatic amines, or (2) metalacetylacetonates, or (3) mixtures of (1) and (2), or (4) mixtures of (2)and triphenylphosphine.

BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to aprocess for the production of dimers of 1,3-butadiene, specifically4-vinylcyclohexene. More particularly, the invention is directed to animproved catalyst system which, in the presence of a conventionaldiluent and polymerization inhibitor, can produce 4-vinylcyclohexenewith relatively high yields, for example, 84% to 91% based on the weightof reacted butadiene.

Conventional catalyst systems described in the prior art include oxides,complex carbonyl compounds, olefins, metal salts, secondary aliphaticamines, metals, as well as ultra-violet radiation. Of those listedherein, the most effective have been found to be dialkyl amines(discussed in US. Pat. No. 2,943,117), metal salts (discussed in US.Pat. No. 2,544,808), and metal, such as iron powder (discussed in GermanPat. No. 949,466).

By the present invention, additional catalyst systems have been found inwhich the yields are consistently above 80%, are reasonably inexpensive,easy to handle, and very effective in the production of4-vinylcyclohexene. Catalyst systems which may be employed are (1)secondary aromatic amines; (2) metal acetylacetonates; (3) mixtures of(1) and (2); or (4) mixtures of (2) and triphenylphosphine. The processis carried out in the presence of up to 60%, based on the weight of the1,3- butadiene, or inert diluent, preferably 12 to 34% by weight, at apressure of atmospheric to 650 p.s.i., preferably 220 to 410 p.s.i., andat a temperature of 100 to 170 0., preferably 120 to 150 C. The inertdiluent may be an aromatic or halogenated aromatic solvent. A small3,526,672 Patented Sept. 1, 1970 amount of a polymerization inhibitor,such as p-tert-butylcatechol, is also conventionally used.

DETAILED DESCRIPTION OF THE INVENTION In order to further illustrate theinvention, reference will be made herein to certain specific exampleswhich are intended to be illustrative, and not in any sense limitmg.

EXAMPLE I A one liter stainless steel autoclave, fitted with a nitrogeninlet and outlet and a thermocouple well, was charged with 5 g. (2.6% byweight based on butadiene charged) of N-phenyl-2-naphthylamine, 0.3 g.of p-tert.-butylcatechol (polymerization inhibitor) and 50 ml. g., 34%by weight) o-dichlorobenzene (diluent). After being flushed withnitrogen to remove all residual air and sealed, the autoclave was cooledin a Dry Ice-acetone bath and charged with 191.7 g. of 1,3-butadiene.The charged autoclave was heated at 130l40 C. for 8 hours. During thistime, the maximum internal pressure was 300 p.s.i., and, after 8 hours,dropped to 220 p.s.i. After 8 hours, the autoclave was left to cool toroom temperature overnight, after which time, unreacted butadiene wasvented from the autoclave. The liquid residue which remained wasfractionated through a glass column (23 x 2 cm.) filled with glasshelices. The yield of 4-vinylcyclohexene (B.P. 127-130 C.) was 85.2%(based on reacted butadiene).

EXAMPLE II A one liter stainless steel autoclave, fitted with a nitrogeninlet and outlet and a thermocouple well, was charged with 10 g. (5.2%by weight) of di-2-naphthylaminc, 0.6 g. of p-tert.-buty1catechol, and32.5 g. (17% by weight) of o-dichlorobenzene (diluent). After theautoclave was flushed with nitrogen to remove residual air and sealed,it was cooled in a Dry Ice-acetone bath, and charged with 193.4 g. of1,3-butadiene. The charged autoclave was heated at 139-141" C. for 8hours, during which time the internal pressure ranged from 390-270p.s.i. The autoclave was left to cool to room temperature overnight, andthe unreacted butadiene removed by venting. The liquid residue whichremained was fractionated asin Example I, and an 88.3% yield of4-vinylcyclohexene was obtained.

Metal acetylacetonates alone and in combination with either secondaryaromatic amines or triphenylphosphine are also effective catalysts inproducing high yields of 4- vinylcyclohexene (4-VC).

By following the procedures of Examples I and II with different catalystsystems, the table below groups together additional examples.

TABLE I.DIMERIZATION OF 1,3-BUTADIENE Inert diluent Re- Catalyst actionInternal Percent Cone, wt. Cone, wt. time, Temp., pressure, yield,

Example No. Name percent Name percent hours C. p.s.i. 4-VC III 1 Pieridine 2.6 Toluene 16. 6 8 135-140 270-420 11. 9 IV N-phenyl-lnaphthylami 5. 2 O-dichlorobenzene 13. 8 8 120-150 310-370 84 8V Ferric actitylacetonaiienan 2 do 13. 8 8 138-141 220-410 85 4 N-pheny-1-naphthy am ne 6 I VI "{gerric acezyiacezona? 2} 8 8 130 150 330439084 1 err e ace y ace ona e.

VII {Triphenylphosphme 13.8 s 130 140 270- 91 3 VIII N-phenyl-1-naphthylami 7. 8 8 -145 240-360 83. 9 IX 1 Diethanolamine 2.68 128-138 260-330 35. 8 X N-phenyl-l-naphthylamine 3. 7 8 134-168340-600 88. 8 XI Di-2-naphthylamine 15. 0 48 100-120 50-220 81. 5 XII-Di-l-naphthylamine 10.0 3 -150 440-550 83. 2 XIIL.N-phenyl-l-naphthylamine 0. 3 Ohlorobenzen 12 130-150 350-450 80, 5XIV.. N-phenyl-2-naphthylamine 5 0 Xyl 6 -170 500-650 90. 3

1 Piperidine and diethanolamine belong to the class of secondaryaliphatic amines which are claimed to be effective catalysts in thisprocess in the prior art. Our experiments have shown that the yields ofii-vinylcyclohexene (4-VC) are much higher when the novel catalysts ofthis invention (secondary aromatic amines, triphenylphosphlne, and/orferric acetylacetonate) are used.

The examples in Table I clearly show that secondary aromatic amines aresuperior to secondary aliphatic amines for use in such catalyst systems.In the absence of any catalyst, no 4-vinylcyelohexene is formed from1,3-butadiene at similar conditions.

While this invention has been described in connection with certainspecific embodiments thereof, it is to be understood that this is by wayof illustration and not by way of limitation; and the scope of theappended claims should be construed as broadly as the prior art willpermit.

What is claimed is:

1. The process of dimerizing 1,3-butadiene to produce 4-vinylcyclohexenewhich comprises maintaining 1,3-butadiene in contact with a catalystselected from the group consisting of (1) secondary aromatic amines; (2)fern'c acetylacetonate; (3) mixtures of (l) and (2); and (4) mixtures of(2) and triphenylphosphine.

2. The process as defined in claim 1, wherein the concentration of saidcatalyst is from 0.3 to 15% by weight, based on the weight of saidbutadiene.

3. The process as defined in claim 2, wherein said reaction ismaintained for at least 3 hours.

4. The process as defined in claim 3, wherein said reaction mixture ismaintained at 100 to 170 C.

5. The process as defined in claim 4, wherein said reaction mixture ismaintained at a pressure of atmospheric to 650 p.s.i.

6. The process as defined in claim 5, wherein said reaction mixture ismaintained in the presence of an inert diluent in a concentration of 0to by weight (based on the weight of said butadiene).

7. The process as defined in claim 6, wherein said inert diluent is anaromatic or halogenated aromatic solvent.

8. The process as defined in claim 1, wherein said secondary aromaticamine is N-phenyl-Z-naphthylamine.

9. The process as defined in claim 1, wherein said secondary aromaticamine is dinaphthylamine.

10. The process as defined in claim 1, wherein said secondary aromaticamine is N-phenyl-l-naphthylamine.

11. The process as defined in claim 1, wherein said catalyst is amixture of N-phenyl-l-naphthylamine and ferric acetylacetonate.

References Cited UNITED STATES PATENTS 2,504,016 4/ 1950 Foster.2,943,117 6/ 1960 Gleason. 2,964,575 12/ 1960 Sekul. 2,991,317 7/ 1961Sellers. 3,187,062 6/ 1965 Shechter. 3,457,319 7/ 1969 Olechowski.3,446,862 5/ 1969 Menapace.

DELBERT E. GANTZ, Primary Examiner V. OKEEFE, Assistant Examiner UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,526,672September 1, 1970 Nicodemus E. Boyer et a1.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 49, "or" should read of Signed and sealed this 23rd dayof March 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E SCHUYLER, JR.

Attesting Officer Commissioner of Patents

